Spinal fusion implant

ABSTRACT

The present invention provides a device and methodology for use in spinal fusion surgeries. An implant is proved for forming a rigid structure between adjoining vertebrae in a patient. The implant is a cage defined by at least a first end, second end, first side, and second side surface, wherein first and second side surfaces extend substantially parallel to each other to span a space between adjoining vertebrae and first and second ends interconnect said first side surface and second side surface. The cage incorporates one or more flexible joints that allow the cage to be deformed for insertion into a patient. The ability to deform the cage allows a greater ease and flexibility in inserting and positioning the implant.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.15/181,542 filed on Jun. 14, 2016, which is a continuation of U.S.application Ser. No. 14/574,441 filed on Dec. 18, 2014 (now U.S. Pat.No. 9,387,091), which is a continuation of U.S. application Ser. No.14/053,821 filed on Oct. 15, 2013 (now U.S. Pat. No. 8,936,643), whichis a continuation of U.S. application Ser. No. 13/230,163 filed on Sep.12, 2011 (now U.S. Pat. No. 8,579,983), which is a continuation of U.S.application Ser. No. 11/496,564 filed on Jul. 31, 2006 (now U.S. Pat.No. 8,034,110), each of which is hereby incorporated by reference in itsentirety.

FIELD OF THE INVENTION

The present invention relates to a spinal implant, the accompanyinginstrumentation and the method of use of both. More particularly, thepresent invention relates to a device and instrumentation for use in aminimally invasive vertebral fusion procedure.

BACKGROUND OF THE INVENTION

Spinal fusion surgeries that use bone graft material to promote specificvertebrae to grow together into a solid and stable construct are acommon method of treating patients with severe back pain. In posteriorlumbar interbody fusion (PLIF), damaged disk material is removed and oneor more implants are inserted posteriorly to promote bone growth fromvertebral body to vertebral body to bridge the gap left by the removedmaterial.

A larger implant better fills the intervertibral space and distributescompressive loads. A larger implant also reduces the need for multipleimplants, which may require multiple approaches to insertion andplacement. However, Minimally Invasive Surgery (MIS) necessitates theuse of less invasive techniques that use smaller access portals toperform the fusion that limit the size of implant that can be used.

An example of this is Transforaminal Posterial Lumbar Interbody Fusion(T-PLIF), which is a variation of the PLIF technique. In this procedure,an implant is inserted through a unilateral or bilateral posteriorapproach. The T-PLIF technique avoids damage to the nerve structuressuch as the dura, cauda equine, and the nerve root, but thetransforaminal window through which the procedure is performed islimited making the insertion and positioning of the implant difficult.

Thus what is needed is an implant that can suitably fill theintervertebral space but can be inserted and positioned through a smallaccess portal, such as the transforaminal window used in a T-PLIFprocedure.

SUMMARY OF THE INVENTION

The present invention provides a device and methodology for use inspinal fusion surgeries. An implant, instrumentation, and methodologyare provided for forming a rigid structure between adjoining vertebraein a patient. The implant is a cage defined by at least a first end,second end, first side, and second side surface. The cage incorporatesone or more flexible joints that allow the cage to be deformed forinsertion into a patient. The ability to deform the cage allows agreater ease and flexibility in inserting and positioning the implant.For example, a larger implant can to be used in minimally invasivesurgery (MIS) techniques because the cage can be transformed to asmaller profile to pass through the smaller access ports used inminimally invasive surgery.

In accordance with one aspect of the present invention, an implant isprovided for forming a rigid structure between adjoining vertebrae in apatient. The implant includes a cage defined by at least a first end,second end, first side, and second side surface, and one or moreflexible joints incorporated into the cage allowing the cage to bedeformed for insertion into a patient.

In certain embodiments, the implant further comprises surfaceconfigurations on at least one of the first and second side surfaces ofthe cage for slidably attaching the implant to an insertion guide. Theone or more flexible joints of the implant allow the cage to conform tothe shape of the insertion guide as the implant is slid along the lengthof the guide.

In accordance with another aspect of the present invention, a method isprovided for fusing vertebrae of a patient. The method involves thesteps of providing an implant of the present invention, and insertingthe implant into the space between adjoining vertebrae in a patient toform a rigid structure between the adjoining vertebrae.

In accordance with another embodiment, a system is proved for forming arigid structure between adjoining vertebrae in a patient. The systemincludes an implant of the present invention having surfaceconfigurations on at least one of the first and second side surfaces ofthe cage for slidably attaching the implant to an insertion guide; andan insertion guide configured to interface with the surfaceconfigurations of the implant for positioning the implant duringinsertion.

In accordance with another aspect of the present invention, a method isprovided for fusing vertebrae of a patient. The method involvesproviding a system of the present invention comprising a implant withsurface configurations and an insertion guide; inserting the insertionguide into the space between adjoining vertebrae in the patient; andsliding the implant along the length of the insertion guide to positionthe implant in the space between adjoining vertebrae, wherein theimplant is slidably attached to the insertion guide by the surfaceconfigurations.

BRIEF DESCRIPTION OF THE FIGURES

The foregoing and other objects, features and advantages of theinvention will be apparent from the following description and apparentfrom the accompanying drawings, in which like reference characters referto the same parts throughout the different views. The drawingsillustrate principles of the invention and, although not to scale, showrelative dimensions

FIG. 1A-1B illustrate one embodiment of an implant having a flexiblejoint.

FIG. 2A-2B illustrate another embodiment of an implant a having a numberof flexible joints.

FIGS. 3A-3B illustrate another embodiment of an implant having anothertype of flexible joint.

FIG. 4 illustrates a flow diagram for an exemplary embodiment of amethod of fusing a spine using the implant of the present invention.

FIG. 5A-5B illustrate another embodiment of an implant having a numberof flexible joints and surface configurations.

FIG. 6 illustrates the deformable nature of the implant of the presentinvention.

FIG. 7 illustrate an embodiment of the system of the present inventionwherein the implant has surface configurations that slidably attach theimplant to an insertion guide.

FIG. 8 illustrates a flow diagram for an exemplary embodiment of amethod of fusing a spine using the system of the present invention

FIGS. 9A-9D illustrate one embodiment of how the implant of the systemof the present invention is inserted by sliding the implant along theinsertion guide as set forth in the exemplary embodiment of the methodof FIG. 8.

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides an improved surgical implant and methodfor performing spinal fusion surgery in a patient. The implant comprisesa cage having one or more flexible joints. The cage is defined by atleast a first end, second end, first side, and second side surface. Thefirst and second side surfaces extend substantially parallel to eachother to span a space between adjoining vertebrae and the first andsecond ends interconnect the first side surface and the second sidesurface. The one or more flexible joints allow the cage to be deformedfor insertion into a patient. The ability to deform the cage allows agreater ease and flexibility in inserting and positioning the implant.For example, a larger implant can to be used in minimally invasivesurgery (MIS) techniques because the cage can be transformed to asmaller profile to pass through the smaller access ports used inminimally invasive surgery. In certain embodiments the implant mayfurther have surface configurations for slidably attaching the implantto a guide used to insert the implant. Embodiments of the implant andmethods of use are described below.

FIGS. 1A and 1B depict one embodiment of an implant 100 for forming arigid structure between adjoining vertebrae in a patient. In thisexample the implant comprises a cage 110 having first end 120, secondend 130, first side 140, and second side 150 surfaces. The first 140 andsecond 150 side surfaces extend substantially parallel to each other tospan a space between adjoining vertebrae. The first 120 and second 130end surfaces interconnect said first side surface 140 and second sidesurface 150. A flexible joint 160 is incorporated into the cage allowingthe cage to be deformed for insertion into a patient. FIG. 1A depictsthe cage 110 of the implant in a rest state. In this example, the first140 and second 150 side surfaces are curved giving the cage a curvedkidney shape. This curvature and shape provide greater coverage andsupport then tradition straight-sided implants and is particularlyadapted for use in a T-PLIF procedure. While, this shape providesgreater biomechanical stability it makes it more difficult to insert andposition due to its increased width.

FIG. 1B shows the cage 110 in a deformed state wherein the first sidesurface 140 has been divided or split at the flexible joint 160 givingthe cage a substantially straight-sided profile. This allows the cageimplant 100 to be used with traditional insertion devices configured tobe used with traditional straight-sided implants.

The cage is designed to provide spacing between adjoining vertebraewhile encouraging bone growth. As such, the cage 110 may be formed ofany biocompatible material suitable for surgical implantation in apatient. Preferably the cage is form of a polymer or composite through aprocess such as injection molding. Bio-compatible metals may also beused to add strength or rigidity. Examples of suitable materialsinclude, but are not limited to, PEAK, carbon fiber, titanium, stainlesssteel, Nitinol, and the like, or any combination thereof.

The cavities 170 created by the cage 110 allow the bone to grow throughthe cage to fuse the vertebrae. In some embodiments a substance, such asbone chips, or bone graft may be placed in the cavities 170 to encouragebone growth.

In the example of FIGS. 1A and 1B, the flexible joint 160 comprises aliving hinge that is formed as part of the cage during the injectionmolding process. In other embodiments, the joint may not be formed aspart of the cage. For example, the cage may comprise two parts that arejoined together using a non-unitary joint mechanism that is embedded inor secured to the two parts. Other implementations and embodiments willbe apparent to one skilled in the art given the benefit of thisdisclosure.

FIGS. 2A and 2B depict another embodiment of the implant 200 of theinvention. As with the implant 100 of FIGS. 1A and 1B this implant 200comprises a cage 210 having first end 220, second end 230, first side240, and second side 250 surfaces. As in the previous embodiment, thefirst 240 and second 250 side surfaces are curved and extendsubstantially parallel to each other to span a space between adjoiningvertebrae. The first 220 and second 230 end surfaces interconnect saidfirst side surface 240 and second side surface 250 providing cavities270 within the cage 210. However, in this embodiment, multiple flexiblejoints 260 are used to allow the cage to be deformed for insertion intoa patient. As with FIG. 1A, FIG. 2A depicts the cage 210 of the implant200 in a rest state with first 240 and second 250 side surfaces curvedto give the cage a curved kidney shape. FIG. 2B shows the cage 210 in adeformed state wherein the first side surface 240 has been divided orsplit at two flexible joints 160 to give the cage a substantiallystraight-sided profile.

Similar to the embodiment of FIGS. 1A and 1B, the flexible joints 260comprise living hinges that are formed as part of the cage during theinjection molding process. In this example the flexible joints 260 alsoinclude a spring mechanism 280 to reinforce the living hinges and returnthe cage 210 to a rest state after being deformed. In this example, thespring 280 is formed of a piece of metal attached to the cage. In otherembodiments, the spring 280 may be formed of plastic or a compositematerial. In certain embodiments, the spring 280 may be embedded in thecage 210 during the formation of the cage 210, for example, duringinjection molding. In other embodiments the spring 280 may be attachedto the cage 210 using adhesive, rivets, or other fastening means. Incertain embodiments the spring 280 may also serve as the flexible joint260. Other embodiments and configurations will be apparent to oneskilled in the art given the benefit of this disclosure.

The example of FIGS. 2A and 2B also includes an opening 225 in the firstend surface 220 for receiving an instrument such as an inserter forattaching the implant to the inserter. In certain embodiments theopening 225 may be in the second end surface 230 or each end surface mayhave such an opening. Examples of inserters the use of inserters inconjunction with implants can be seen in WO2005077288 A1

While many of the examples and embodiments discussed in this disclosurefocus on curved or kidney-shaped implants, it should be understood thatthe teaching of the invention are not limited to such shapes. FIGS.3A-3B depict another example of other possible shapes and flexiblejoints.

FIGS. 3A and 3B are a top view depicting a straight sided square shapedimplant 300. In this example, flexible joints are used to connect thefirst 340 and second 350 side surfaces to the first 320 and second 330end surfaces of the cage 310. This allows the cage 310 to be transformeddown to a smaller size as shown in FIG. 3B. The ability to transform thecage 310 allows the cage to be inserted through a smaller access portfor insertion in between vertebrae.

FIG. 4 is a flow chart 400 of an exemplary method for fusing vertebraeof a patient. The method involves substantially the steps of providingan implant of the present invention (step 420) and inserting the implantinto the space between adjoining vertebrae in a patient to form a rigidstructure between the adjoining vertebrae (step 430).

In some embodiments the method 400 may further include the steps ofpreparing the space between adjoining vertebrae (step 410) as well asthe steps of transforming the cage of the implant to a smaller profile(step 425) before implantation and transforming the cage back to theoriginal profile after insertion (435).

The step of preparing the space between adjoining vertebrae (step 410)may include removing the disk material between the vertebrae. Then thespace between the vertebrae may be distracted to relieve pressure fromneural elements and provide space for the entry of surgical tools andthe insertion of the implant. Preferably the surgery including theinsertion is performed using a MIS technique such a T-PLIF procedure.

Because MIS techniques such as T-PLIF procedures use a more limitedaccess port or window, the cage of the implant may need to betransformed or otherwise deformed in order to fit through the accessport or window (step 425) and be positioned in the space betweenvertebrae. Once in position, the cage may then be transformed back orotherwise returned to its rest state (step 435). In certain embodimentsthis is performed by a spring incorporated or attached to the one ormore flexible joints.

In some embodiments, the implant 500 may further include surfaceconfigurations 590 on at least one of the first 540 and second 550 sidesurfaces of the cage 510 for slidably attaching the implant 500 to aninsertion guide. An example of this can be seen in FIGS. 5A and 5B. Herethe surface configurations 590 are tabs or fingers formed on the firstside surface 540. When used in conjunction with an insertion guide, theflexible joints 560 of the implant 500 allow the cage 510 to deform(i.e. straighten) to conform to the shape of the insertion guide. Thisis described in more detail below.

In the embodiments of FIGS. 5A and 5B, the cage 510 further includestextured edges 515 on the first end 520, second end 530, first side 540,and second side 550 surfaces for engaging the bone of the adjoiningvertebrae to secure the implant in place in the space between vertebrae.Other possible configurations and textures for securing the implant 500will be apparent to one skilled in the art given the benefit of thisdisclosure.

FIG. 6 depicts one advantage of the cage 510 of the implant being ableto deform. The ability of the implant 500 of the present invention todeform allows the profile of the cage to be transformed to a smallerprofile. When thus transformed, the implant can be passed through apassage smaller than what is required by a traditional curved implant600. As shown here, the deformed (compressed) implant 500 (includingsurface configurations) requires only 11.9 mm of space as opposed to the12.7 mm of space required for a fixed, non-deformable, curved implant600 of the same size.

In another embodiment of the present invention, a system is provided forforming a rigid structure between adjoining vertebrae in a patient. Anexample of such a system can be seen in FIG. 7. The system 700 includesan implant 500 of the present invention as shown in FIGS. 5A and 5Bhaving surface configurations 590 for slidably attaching the implant 500to an insertion guide 710. As shown in this embodiment, the flexiblejoints 560 of the implant may allow the cage 510 to conform to the shapeof the insertion guide 710. In this case the cage 510 is deformed so asto have a smaller straight-sided profile when attached to a straightportion of the insertion guide 710.

In certain embodiments, such as shown in FIG. 7, the insertion guide 710may have a curved end 720 to further assist in the insertion andpositioning of the implant 510. In use, when the implant is slid alongthe insertion guide 710 in the direction of arrow 730, the flexiblejoints 560 of the implant 500 allow the implant to curve to conform tothe curved end 720 of the insertion guide 710. The implant 500 may slidealong the insertion guide 710 using an inserter configured to mate withopening 525.

FIG. 8 is a flow chart 800 of an exemplary method for fusing vertebraeof a patient. The method involves substantially the steps of providing asystem of the present invention having an implant with surfaceconfigurations and an insertion guide (Step 820), inserting theinsertion guide into the space between adjoining vertebrae (Step 830),and sliding the implant along the length of the insertion guide toposition the implant in the space between adjoining vertebrae, (Step840).

In some embodiments the method 800 may further include the steps ofpreparing the space between adjoining vertebrae (Step 810) as well asthe step of removing the insertion guide after the implant has beeninserted (Step 850).

The step of preparing the space between adjoining vertebrae (Step 810)may include removing the disk material between the vertebrae. Then thespace between the vertebrae may be distracted to relieve pressure fromneural elements and provide space for the entry of surgical tools andthe insertion of the implant. Preferably the surgery including theinsertion is performed using a MIS technique such a T-PLIF procedure.

Examples of this methodology using a T-PLIF technique can be seen inFIG. 9A-D. Because MIS techniques such as T-PLIF procedures use a morelimited access port or window 910, the insertion guide with a curved tip720 is used to deform and guide the implant 500 so as to be insertedinto and positioned in the space 920 between vertebrae as seen in FIG.9A.

In FIG. 9B, the implant is slid along the length of the insertion guide710. The implant 600 may be slid along the insertion guide 710 using aninsertion tool (not shown) mated with the opening 525 configured toreceive the insertion tool. Examples of suitable insertion devices andtheir use is discussed in WO2005077288 A1.

In FIG. 9C, the insertion guide 710 is used to guide the implant 500through the access window 910 and position the implant in location inthe space 920 between vertebrae. The use of the curved tip 720 allowsthe implant 510 to be positioned at a desired angle, preferably around45°, even though the angle of approach through the access window 910 maybe closer to 35°.

Once in position, the insertion guide 710 may be removed and the implantallowed to transform or otherwise return to its rest state as seen inFIG. 9D. In certain embodiments this is performed by a springincorporated or attached to the one or more flexible joints.

The apparatus and techniques of the present invention provide numerousadvantages. The implant of the present invention can be used inminimally invasive surgery (MIS) wherein the cage can be deformed foreasier insertion and positioning through a smaller access port. Incertain embodiments, the cage may have surface configurations for usewith an insertion guide. The cage of the implant can be deformed toconform to the shape of the guide which allows for curved guides whichin turn provide more accurate insertion and positioning.

Although, the present invention has been described relative to anillustrative embodiment and application in spinal correction surgery. Itshould be apparent that the present invention may be used in any numberof surgical procedures. Since certain changes may be made in the aboveconstructions without departing from the scope of the invention, it isintended that all matter contained in the above description or shown inthe accompanying drawings be interpreted as illustrative and not in alimiting sense.

It is also to be understood that the following claims are to cover allgeneric and specific features of the invention described herein, and allstatements of the scope of the invention which, as a matter of language,might be said to fall therebetween.

The invention claimed is:
 1. A method for fusing vertebrae of a patient,comprising: forming an access window into a disc space between first andsecond vertebrae of the patient; inserting an insertion guide into thedisc space along an insertion axis, the insertion guide having aproximal end portion that is parallel to the insertion axis and a distalend portion that is not parallel to the insertion axis, the insertionguide being positioned such that the distal end portion is disposed inthe disc space; positioning an implant having proximal and distal endsand a plurality of flexible joints in a first state in which opposedlateral sidewalls of the implant are substantially straight; passing theimplant through the access window and into the disc space; sliding theimplant within the disc space to position the proximal and distal endsof the implant within the disc space, the guide being attached to theimplant to guide sliding of the implant and to flex the plurality offlexible joints of the implant and transition the implant to a secondstate in which the opposed lateral sidewalls of the implant are curved;and filling a cavity defined by the implant with graft material.
 2. Themethod of claim 1, wherein sliding the implant comprises pushing theimplant along the insertion axis using an inserter instrument coupled toa trailing end of the implant.
 3. The method of claim 1, wherein aleading end of the implant is tapered.
 4. The method of claim 1, whereinthe implant has a smaller profile in the first state than in the secondstate.
 5. The method of claim 1, wherein the cavity is configured toallow bone ingrowth.
 6. The method of claim 1, further comprisingdistracting the disc space.
 7. The method of claim 1, wherein the accesswindow comprises a transforaminal window.
 8. The method of claim 1,wherein the implant in the second state has a curved kidney shape. 9.The method of claim 1, wherein the implant includes a plurality ofseparate parts that are joined together by non-unitary joint mechanismssecured thereto.
 10. A method for fusing vertebrae of a patient,comprising: forming an access window into a disc space between first andsecond vertebrae of the patient; inserting an insertion guide throughthe access window and into the disc space to position a distal endportion of the insertion guide in the disc space, the distal end portionof the insertion guide being curved in a transverse plane of thepatient; sliding an implant coupled to the insertion guide into the discspace to position proximal and distal ends of the implant in the discspace; and translating the implant within the disc space, the insertionguide causing the implant to flex at a plurality of joints of theimplant and thereby transition the implant from a first configuration inwhich the implant is not curved in the transverse plane of the patientto a second configuration in which the implant is curved in thetransverse plane of the patient.
 11. The method of claim 10, furthercomprising filling a cavity defined by the implant with graft material.12. The method of claim 10, wherein translating the implant comprisespushing the implant into the disc space using an inserter instrumentcoupled to a trailing end of the implant.
 13. The method of claim 10,wherein a leading end of the implant is tapered.
 14. The method of claim10, wherein the implant has a smaller profile in the first configurationthan in the second configuration.
 15. The method of claim 10, whereinthe implant defines a cavity configured to allow bone ingrowth.
 16. Themethod of claim 10, further comprising distracting the disc space. 17.The method of claim 10, wherein the access window comprises atransforaminal window.
 18. The method of claim 10, wherein the implantin the second configuration has a curved kidney shape.
 19. The method ofclaim 10, wherein the implant includes a plurality of separate partsthat are joined together by non-unitary joint mechanisms securedthereto.